Magnetic transducer head



Feb. 7, 1961 A. E. LORENZ MAGNETIC TRANSDUCER HEAD Filed Feb. 18, 1955 I N V EN TOR. 42)"??4 E Iowan;

United States Patent MAGNETIC TRANSDUCER HEAD Alfred E. Lorenz, Algonquin, Ill., assignor to Comptometer Corporation, a corporation of Illinois Filed Feb. 18, 1955, Ser. No. 489,201

16 Claims. (Cl. 274-20) This invention relates in general to transducer apparatus and has more particular reference to a carriage for the transducer head for such apparatus.

An object of the invention is the provision in such apparatus of a novel and improved carriage for the transducer head.

Another object of the invention is the provision in such apparatus of a swingable carriage for swinging a magnetic transducer head between a transducing position and a non-transducing position, which is releasably latched in each of those positions when moved thereto.

A further object of the invention is the provision in such apparatus of means for automatically separating the elements of the head-traversing drive connection as the head is moved by the carriage toward its non-transducing position to permit reciprocation of the head transversely of the signal receiving or bearing member without interference from the head-traversing drive connection and without undue wear of or injury to the elements thereof.

Another object of the invention is the provision in such apparatus of a carriage for the transducer head wherein the contact force between the elements of the headtraversing drive connection is independent of the weight of the head.

Yet another object of the invention is the provision in such apparatus of a carriage for the transducer head wherein the contact force between the elements of the head-traversing drive connection is not increased by the movement of the head from its non-transducing position toward its transducing position.

A further object of the invention is the provision in such apparatus of a novel swingable carriage for swinging a magnetic-type transducer head between transducing and non-transducing positions correspondingly to move a member to actuate means for releasably latching the transducer element in each of those positions when moved thereto and to actuate means for disrupting drive relationship between the separable elements of the head-traversing drive connection While the head is being moved toward its non-transducing position.

Other objects of the invention will become apparent from the following description and claims and are illustrated in the accompanying drawing which by way of illustration shows a presently preferred embodiment of the invention.

In the drawing:

Figure 1 is a fragmentary side view, partially in crosssection, of transducer apparatus embodying the features of the invention, and shows a side view of the transducer head and carriage therefor in full lines in transducing position and in broken lines in non-transducing position;

Fig. 2 is a front view of the novel carriage of the transducer head shown in Fig. 1;

Fig. 3 is a cross-sectional view of the novel carriage for the transducer head taken substantially along the lines 33 of Fig. 1;

Fig. 4 is a cross-sectional view taken substantially along the lines 44 of Fig. 1 on an enlarged scale to 2,970,843 Patented Feb. -7, 1961 bring out certain details of the head-traversing drive connection;

Fig. 5 is a fragmentary side view like Fig. 1, partially in cross-section, and shows the transducer head and carriage therefor in non-transducing position; and

Fig. 6 is a side view of the novel carriage for the transducer head shown in Fig. 1.

Transducer apparatus of the type to which this invention relates usually comprises, as shown in Figs. 1 and 5, a transducer head A, a rod or other suitable support B therefor, a drivable carrier C for removably carrying and driving signal receiving or bearing member or means D, and a head-traversing drive connection E including a rotatable threaded shaft or feed screw F. In such apparatus, the head A is pivotally and slidably mounted on the support B in cooperative relationship with the signal receiving or bearing member D. The transducer head is thus swingable between a transducing position (full lines in Fig. 1) and a non-transducing position (broken lines in Fig. l) with respect to the signal receiving or bearing member D on the carrier C. When the head A is in its transducing position, it is movable by the head-traversing drive connection E along the support B to traverse the signal receiving or bearing member D for recording or reproducing signals thereon. When that head is in its nontransducing position, it is reciprocable along the support B to position thevhead for a subsequent traversing movement transversely of the member D.

While the transducer apparatus including the support B, carrier C, signal receiving or bearing member D, and feed screw F may be of various types, I presently prefer that disclosed in my copending United States Letters patent application Serial No. 408,907, filed February 8, 1954 as illustrative of transducer apparatus in which the present invention may be embodied to advantage. As will be understood from that patent application, the transducer apparatus comprises suitable supporting, driving, control, amplifier, and easing means none of which per se constitutes any part of the present invention and none of which, therefore, is shown in the accompanying drawing or described in detail herein.

As in my above-mentioned patent application, preferably the transducer head A is of the magnetic type; the carrier C is a rotatable drive roll; the signal receiving or bearing member D is an endless belt adapted to have magnetic signals recorded thereon along a helical path and to have such signals reproduced by the transducer head; the rotatable drive roll C, the rod B, and the rotatable feed screw F are mounted parallel to one another with the rod above and slightly forwardly of the feed screw and with the drive roll forwardly of and slightly below the rod; and the rotatable drive roll C and the rotatable feed screw F are adapted to be rotated in timed relationship during a transducing operation.

Illustrative of the invention as shown in the accompanying drawing, the transducer head A is attached to a bell-crank lever 11. As shown in Figs. 5 and 6, the bellcrank lever 11 is preferably constructed of two members 12 and 13. The member 12 constitutes an arm of the bell-cranak lever and is cast or otherwise formed with a handle portion 14 and a mounting portion 15 at its opposite ends and, intermediate its ends, with a casing portion 16 in which the transducer head is mounted by any suitable means and from which it depends through the bottom side thereof. Electrical conductors 17 connected to the transducer head are connectible to a suitable electric circuit for energizing the head during a recording operation and for transmitting electrical impulses correlated with the recorded signals during a reproducing operation.

The member 13 is substantially L-shaped and is cast or otherwise formed with a mounting arm 18 and an arm 19. As shown in Fig. 5, the mounting portion 15 of the member or arm 12 is fixed by screws 21 or other suitable securing means in engagement with one side of the mounting arm 18 of the member 13, with the arm 19 thereof near the inner end of the mounting portion 15 and extending therefrom at substantially right angles to the member or arm 12 to constitute anarm of the bellcrank lever 11. Near the adjacent ends of the arms 18 and 19, the member 13 is provided with an aperture 22 extending therethrough in a direction normal to those arms of the member 13. Extending through that aperture 22 and beyond the opposite sides of the member 13 is a tubular member 23 to which the bell-crank lever 11 is fixed by, for example, a set screw 24 to provide a carriage G (Fig. 6) for the transducer head A, and which is slidably and rotatably receivable on the rod B. Preferably the tubular member 23 is provided at opposite sides of the bell-crank lever with adjustable, aligning bearing means 25 of the type disclosed in my abovementioned patent application for minimizing friction between the tubular member and the supporting rod and for maintaining them in coaxial relationship.

To the end portion of the bell-crank lever arm 19 opposite its end adjacent the mounting arm 18, there is secured by screws 26 or other suitable fastening means a substantially bshapcd resilient member or spring 27 having a spring arm 28 extending in the same direction from the lever arm 19 as the mounting arm 18 and in substantially parallel relationship to that arm 18. At the end of the spring arm 28 remote from the lever arm 19, the spring 27 is provided with a cam-shaped detent 29 for cooperating with a relatively stationary latch member 31 to releasably latch the transducer head A in each of its transducing and non-transducing positions when moved thereto.

As shown in Figs. 1 and 5, the relatively stationary latch member 31 is an end of an arm 32 mounted on the carriage G for sliding movement therewith. The arm 32 is stamped or otherwise formed at its opposite end with spaced parallel tabs 33 having coaxial apertures 34 therethrough for pivotally mounting the arm on the tubular member 23 with one of the tabs 33, 'as shown in Fig. 3, outwardly adjacent one side of the member 13 and with the other of the tabs 33 spaced outwardly from the opposite side of the member 13 by a distance slightly greater than the thickness of the tab. When so mounted, the arm 32 extends in the same direction from the tubular member 23 as does the lever arm 19 and into cooperative relationship with the cam-shaped detent 29.

Intermediate its ends, the arm 32 has secured thereto by a screw 35 or other suitable securing means a plate 36. That plate is stamped or otherwise formed with an intermediate portion 37 extending laterally from the arm length as to extend beyond the arm 32 and to serve as 32 toward the lever arm 19 and an inclined end portion 38 converging from the end of the intermediate portion nearer the lever arm 19 toward that lever arm. .Between the arm 32 and the inclined end portion 38 of the plate 36, there is thus provided a space adapted to receive therein the feed screw F with the arm 32 and the inclined end portion 38 slidably engaging opposite sides of the feed screw whereby the end of the arm 32 constituting the latch member 31 will be maintained substantially stationary relative to the cam-shaped detent 29.

That inclined end portion 38 of the plate 36 is provided with a slot 39 extending from its end nearer the lever arm 19 toward the intermediate portion 37 of the plate 36 and dividing that end of the inclined end portion into a relatively wide and short tab 41 and a narrower and longer tab 42, as shown in Fig. 3. The side of the tab 41 adjacent the slot 39 is substantially in alignment with one side of the lever arm 19 and that tab 41 extends from the slot along the feed screw F a distance greater than the width of the lever arm 19. If desired, where the screw 35 is employed to secure the plate 36 to the arm 32, the screw is provided of such to indicate the limit of the traversing movement of the 'head A relative to the member D, as disclosed in my above-mentioned patent application.

Mounted on the carriage G for sliding movement therewith along the rod B is an arm 43 which is similar in construction to the arm 32. The arm 43 is stamped or otherwise formed at one end with spaced parallel tabs 44 having coaxial apertures 45 therethrough for pivotally mounting the arm on the tubularmember 23 with one of the tabs 44, as shown in Fig. 3, between the member 13 and the tab 33 spaced outwardly from a side thereof and with the other of the tabs 44 outwardly adjacent the tab 33 adjacent the opposite side of the member 13. When so mounted, the arm 43 extends in the same direction from the tubular member 23 as does the arm 32, the lower end portions of those arms 32 and 43 being in substantially parallel, aligned relationship, with the lever arm 19 and the plate 36 therebetween.

Intermediate its ends, the arm 43 has riveted or otherwise secured thereto a channel member stamped or otherwise formed with a relatively wide flange 46, a narrower flange 47 parallel thereto and sufficiently spaced therefrom to receive the lever arm 19 therebetween, and a transverse connecting portion 48 adjacent the face of the arm 43 nearer the lever arm 19. At one side of the lever arm 19, the flange 46 extends from the arm 43 a distance greater than the thickness of the lever arm and in alignment with the slot 39 in the inclined end portion 38 of the plate 36 and is movable into and out of that slot when the transducer head is moved to its transducing and non-transducing positions, respectively.

At the opposite side of the lever arm 19, the narrower flange 47 extends from the arm 43 a distance greater than the thickness of the lever arm and is engageable with and disengageable from the relatively wide and short tab 41 of the inclined end portion 38 of the plate 36 when the transducer head is moved to its transducing and nontransducing positions, respectively. The marginal portion of the flange 46 opposite the connecting portion 48 is of such thickness as to be receivable in the thread grooves of the feed screw F, thus adapting the flange 46 to serve as a screw follower in the head-traversing drive connection E.

As will be understood from the foregoing description, the lever arm 19 is engageable with the connecting portion 48 between the flanges 46 and 47 to move them and hence the arm 43 in a direction away from the plate 36 as the transducer head is moved toward its nontransducing position. For moving those flanges 46 and 47 in the opposite direction, a coil spring 49 is secured at one end to the arm 43 below the flanges 46 and 47 and at its other end to a relatively stationary member, such as the arm 32 below the plate 36.

As shown in Figs. 1 and 5, the carriage G is arranged on the rod B with the rod extending through the tubular member 23 of the carriage and with the arm 32 depending therefrom in sliding engagement with the feed screw F at the rear side thereof, the inclined end portion 38 of the plate 36 being in sliding engagement with the forward side of the feed screw. When the carriage G is so mounted on the rod B, the lever arm 19 is spaced forwardly of the feed screw F, the arm 43 is adjacent the forward face of the lever arm 19, and the member 12 of the bell-crank lever 11 extends forwardly under a stationary member 51 to position the transducer head A in adjacent, substantially tangential relationship with the rotatable carrier C. For convenience a portion of the casing (not shown herein) of the transducing apparatus may, as disclosed in my above identified patent application, be employed as the stationary member 51 for engagement by .the member 12 to limit the movement of the transducer head in a direction away from the transducing position.

west:

As shown by the full lines of Fig. 1, the transducer head A is in its transducing position, i.e. in engagement with the signal receiving or bearing member D on the carrier C. When the transducer head is in that position, the cam-shaped detent 29 of the spring 27 is rearwardly of the latch member 31, and the coil spring 49 yieldably holds the follower flange 46 in engagement with the threads of the rotatable feed screw F. Rotation of the feed screw while the follower flange is thus in engagement therewith will cause the follower flange to be moved along the feed screw. Since the follower flange 46 is secured to the arm 43, the follower flange in so moving moves the arm 43 with it and thereby moves the carriage G, on which the arm 43 is pivotally mounted as already described, the tubular member 23 of the carriage sliding along the rod B and carrying with it the arm 32 pivotally mounted on and depending from the tubular member.

The carriage G and the arms 32 and 43 are thus moved along the rod B while the transducer head A is in its transducing position. When the signal receiving or bearing member D is driven by the rotatable carrier C while the carriage G is so moved in that position, the transducing head moving with the carriage traverses the signal receiving or bearing member to perform a transducing operation.

By means of the handle portion 14 of the member 12, the bell-crank lever 11 of the carrier G is swingable about the rod B in a direction (clockwise in Figs. 1 and 5) to move the transducer head A from its transducing position to its non-transducing position, i.e. in spaced relationship with the signal receiving or bearing member D on the carrier C. During such swinging of the bell-crank lever, its depending lever arm 19 is moved forwardly (Fig. 1), engaging the connecting portion 48 of the channel member having the follower flange 46 and moving that connecting portion and follower flange and hence the depending arm 43 forwardly. During the forward movement of the depending arm 43 and the follower flange 46 carried thereby while the transducer head A is thus being swung toward its non-transducing position, the follower flange is separated from and moved forwardly of the feed screw F, thus disrupting the drive relationship between the follower flange and feed screw of the head-traversing drive connection E. The engagement of the arm 32 with the rear side of the feed screw F prevents forward movement of that arm 32 during such forward movement of the depending lever arm 19 and arm 43, the coil spring 49 yielding to permit the relative movement between the arms 32 and 43.

Further forward movement of the lever arm 19 while the transducer head is being swung to its non-transduc ing position causes the cam-shaped detent 29 of the spring 27, secured to and moving forwardly with the lever arm 19, in cooperation with the relatively stationary member 31 to cam the spring arm 28 downwardly, as viewed in Fig. 1, to permit the detent to move forwardly beyond the stationary member. As the camshaped detent 29 is thus moved forwardly beyond the stationary member 31, Fig. 5, the cam-shaped detent is moved upwardly by the resiliency of the spring 27 to engage the forward side of the stationary member 31 and releasably latch the lever arm 19 in such a forward position as to hold the transducer head A in its nontransducing position.

While the transducer head A is thus releasably held in its non-transducing position, the follower flange 46, as shown in Fig. 5, is in forward spaced relationship to the threads of the feed screw F and the extended coil spring 49 urges the arm 43 rearwardly toward the feed screw F. The arm is, however, releasably held against rearward movement by the lever arm 19. Consequently, by means of the handle portion 14, the carriage G is freely reciprocable along the rod B to adjust the transducer head to any position transversely of the signal receiving ortransmitting member C without interference from the head traversing drive connection E and without wear or injury to the separated follower flange 46 or feed screw F thereof.

By means of the handle portion 14 of the member 12, the bell-crank lever 11 of the carriage G is swingable about the rod B in a direction (counterclockwise in Figs. .1 and 5) to move the transducer head A from its nontransducing position to its transducing position. During such swinging of the bell-crank lever, its depending lever arm 19 is moved rearwardly (Fig. 5) moving with it the cam-shaped detent 29 of the spring 27. The rearwardly moving cam-shaped detent 29 cooperates with the relatively stationary member 31 to cam the spring arm 28 downwardly, as viewed in Fig. 5, to permit the detent 29 to move beyond the stationary member 31. Such rearward movement of the lever arm 19 and swing ing of the transducer head continues until the latter reaches its transducing position at which the lever arm 19 engages the tab 41 of the plate 36, the end portion 38 of which is held stationary by engagement with the feed screw F. As the cam-shaped detent 29 is thus moved rearwardly beyond the stationary member 31, the detent is moved upwardly, as viewed in Fig. 5, by the resilience of the spring 27 to cooperate with the rear side of the stationary member 31 for releasably latching the lever arm 19 in such a rearward position as to hold the transducer head A in its transducing position.

Such rearward movement of the lever arm 19 frees the depending arm 43 for rearward movement. When that occurs, the coil spring 49 moves the depending arm 43 rearwardly to move the follower flange 46 into engagement, through the slot 39, with the feed screw F to establish the drive relationship between the follower flange and feed screw of the head-traversing drive connection E. As that drive relationship is established or, as the case may be, re-established, the flange 47 moving rearwardly with the lever arm 19 engages the tab 41 of the plate 36 to limit the rearward movement of the follower flange 46 and the arm 43 carrying the flanges 46 and 47.

It will thus be understood that the tab 41 limits rearward movement of the lever arm 19. Consequently, the contact force between the transducer head A and the signal receiving or bearing member D on the carrier C is substantially independent of the weight of the head and its casing and of the force with which the head is moved to its transducing position. Likewise, since the tab 41, when engaged by the flange 47, limits rearward movement of the follower flange 46, the contact force between it and the feed screw when the transducer head is in its transducing position is substantially independent of the weight of the transducer head and its casing and of the force with which the follower flange 46 is moved into drive relationship with the feed screw F.

It is thought that the invention and its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement-of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described and illustrated in the drawing being merely a preferred embodiment thereof.

I claim:

1. In transducer apparatus, a carriage mounted for pivotal movement and for transverse movement normal to the direction of the pivotal movement, a transducer head rigid with and carried by said carriage and movable there'- with during pivotal movement thereof between a trans ducing position and a non-transducing position, latch means on said carriage and operable by said transducer head during pivotal movement thereof as it moves between its transducing and non-transducing positions for releasably latching said transducer head in each said position when moved thereto, a feed screw, and means form into and out of driving engagement with said feed screw for forming said connection and movable out of such engagement by said carriage while it is moving said transducer head toward its non-transducing position to thereby disconnect said connection, said latch means including an element fixed relative to pivotal movement of said transducer head, and the latch means being operative for maintaining said movable member in disconnected position when said transducer head is in non-transducing position.

2. In transducer apparatus, a transducer head having transducing and non-transducing positions, a rotatable feed screw, a rigidand unitary bell-crank lever mounted for pivotal movement about an axis in spaced parallel relationship with said feed screw at a side thereof and having a lever arm carrying said transducer head, said bell-crank lever being swingable about said axis by said lever arm to move said transducer head between its transducing and non-transducing positions and being reciprocable along said axis by said lever arm while said transducer head is in its non-transducing position to adjust said transducer head to any position along said axis, a member in spaced relationship with said feed screw at a side thereof adjacent its first said side and pivotally mounted on said bell-crank lever for pivotal movement about said axis and reciprocable therealong with said lever, said member having a feed-screw follower engageable with said feed screw to impart to said bell-crank lever and transducer head movement along said axis, yieldable means separate from said transducer head and bell-crank lever urging said member toward said feed screw for yieldably holding said follower in engagement therewith, said bell-crank lever having another lever arm between said member and said feed screw swingable by the first said lever arm while the latter is moving said transducer head toward its non-transducing position to swing said member in a direction away from said feed screw for disengaging said follower therefrom, and stop means reciprocable by said bell-crank lever along said axis for limiting pivotal movement of said bell-crank lever in direction for moving said transducer head to its said transducing position.

3. In transducer apparatus as set forth in claim 2, a latch member fixed relative to pivotal movement of said bell-crank lever and said member, and a detent swingable with said other lever arm and cooperating with said latch member releasably to latch said bell-crank lever against return pivotal movement whereby releasably to hold said transducer head in its non-transducing position when it is moved thereto.

4. In transducer apparatus as set forth in claim 3, latch means including a detent on and swingable with said other lever arm for releasably latching it when swung by the first said lever arm away from said feed screw releasably to hold said follower out of engagement with said feed screw.

5. In transducer apparatus according to claim 3 wherein said latch member comprises an arm pivotally mounted on said bell-crank lever and reciprocable along said axis with said lever, said arm slidably engaging the side of said feed screw opposite said member and having a member extending from said arm transversely of said feed screw into sliding engagement with the opposite side thereof.

6. In transducer apparatus, a transducer head having transducing and non-transducing positions, a rotatable feed screw, a bell-crank lever mounted for pivotal movement about an axis in spaced parallel relationship with said feed screw at a side thereof and having a lever arm carrying said transducer head, said bell-crank being swingable about said axis by said lever arm to move said transducer head between its transducing and non-transducing positions, a member in spaced relationship with said feed screw at a side thereof adjacent its first said side and pivotally mounted on said bell-crank lever to swing about said axis, said member having a feed screw follower engageable with said feed screw to impart to said bell-crank lever and transducer head movement along said axis, resilient means urging said member toward said feed screw for yieldably holding said follower in engagement therewith, said bell-crank lever having another lever arm between said member and said feed screw swingable by the first said lever arm while'the latter is moving said transducer head toward its non-transducing position to swing said member against the action of said resilient means away from said feed screw for disengaging said follower therefrom, said resilient means being adapted to swing said member toward said feed screw for re-engaging said follower therewith while the first said arm is swinging said lever to move said transducer head to its transducing position, and means pivotally mounted on said bell-crank lever and reciprocable along said axis with said lever and having an arm slidably engaging the side of said feed screw opposite said member and an arm slidably engaging the opposite side of said feed screw to prevent pivotal movement of the last said means and a portion engageable by said follower engaging said feed screw to limit the engaging force therebetween.

7. In transducing apparatus, a transducer head, a sup porting rod, a carriage rigidly mounting said transducer head and supported on said rod for pivotal movement thereon for thereby moving said transducer head between a transducing position and a non-transducing position, and for sliding movement along said rod, a feed screw, :1

first arm mounted on said rod and movable therealong by said carriage and having an end portion engaging said feed screw and restrained thereby against pivotal move ment about said rod, said carriage having an operating arm adjacent said feed screw and engageable with said end portion and being thereby limited in movement in direction for moving said transducer head to transducing position, a third arm pivoted on said rod and moveable along the rod by said carriage and positioned on and engageable with the side of said operating arm opposite said feed screw and having a screw following portion engageable with said feed screw, and means biasing said third arm into engagement with said feed screw, said end portion of the first arm serving as stop means for limiting movement of said third arm into engagement with said feed screw.

8. Transducer apparatus as set forth in claim 7, wherein said third arm includes a channel portion having flanges straddling said operating arm, one of which is engageable with said first arm and the other of which engages the threads of said feed screw, and wherein a latch element is secured on the swinging end of said operating arm and is cooperable with said first arm for latching said carriage in positions of movement about the axis of said rod.

9. In transducer apparatus, a carriage mounted for pivotal movement and for movement transversely of the direction of the pivotal movement, a magnetic-type transducer head on said carriage and movable therewith during pivotal movement thereof between a transducing position and a non-transducing position, said transducer head being rigidly connected to said carriage and having a fixed and rigid element disposed in a predetermined position when said transducer head is in its said transducing position, driving and driven members engaging each other to impart transverse movement to said carriage and said transducer head thereon, one of said members being mounted for movement to separated spaced relationship relative to the other of said members to disrupt the driving relationship therebetween, operating means rigid with said transducer head and pivotally movable thereby during pivotal movement thereof for moving the movable one of said members to separated spaced relationship relative to the other of said members while said transducer head is moving toward its non-transducing position, said transducer head and operating means being unitarily and rigidly interconnected and adapted for conjoint movement in either direction of pivotal movement in response to manually grasping the transducer head and so moving it,

and stop means stationary and fixed relative to pivotal movement of the transducer head engageable by said operating arm.

10. In transducer apparatus, as set forth in claim 9, latch means including a detent movable with said transducer head during pivotal movement thereof as it moves toward its non-transducing position for releasably latching said transducer head in that position when moved thereto and for releasably latching said movable one of said members in separated spaced relationship relative to the other of said members.

11. In transducer apparatus, as set forth in claim 10, means energized by said operating means during its movement of the movable member to separated spaced relationship relative to said other member for returning said movable member into engagement with said other member.

12. In transducer apparatus, a magnetic-type transducer head having a transducing position and a nontransducing position, a carriage carrying said transducer head and mounted for pivotal movement for moving it between the transducing and non-transducing positions and for transverse movement normal to the direction of the pivotal movement, driving and drivable members engageable with each other, one of said members being mounted for movement relative to the other between engaged relationship therewith to impart transverse movement to said carriage and spaced relationship from said other member to disrupt the driving relationship between said members, operating means pivoted on said carriage rigid with said transducer head and movable thereby during pivotal movement thereof for moving the movable one of said members from engaged relation with the other said member while said carriage moves said transducer head toward its non-transducing position, means connected between said movable member and an element fixed relative to pivotal movement of said movable member for moving said movable member to engaged relationship with said other member when said carriage means moves said transducer head to its transducing position, latch means including a detent movable with said carriage during pivotal movement thereof as it moves said transducer head between its transducing and non-transducing positions for releasably latching said transducer head in each of said positions when moved thereto, and stop means including an element fixed relative to pivotal movement of said transducer head for rigidly limiting movement of said transducer head to its transducing position.

13. In transducer apparatus, a transducer head, a carriage mounting said transducer head and pivotally movable about an axis between a first and a second posi tion for moving said transducer head between a transducing position and a non-transducing position, respectively, said carriage and transducer head forming a rigid sub-assembly, and also movable longitudinally along said axis, a feed screw, a screw follower on said carriage and movable relative thereto, means biasing said screw follower into engagement with said feed screw, said screw folfower being moved out of engagement with said feed screw by said carriage when the latter moves said transducer head to non-transducing position, stop means separate from said sub-assembly and fixed relative to pivotal movement of said carriage for limiting movement of said carriage to its said first position, and second stop means also fixed relative to said pivotal movement, and separate from the feed screw, for limiting movement of said screw follower into engagement with said feed screw.

14. Transducer apparatus as set forth in claim 13, wherein said stop means are movable along said axis by said carriage.

15. Transducer apparatus as set forth in claim 14, wherein said stop means include an element restrained by said feed screw against movement in the directions of pivotal movement of said carriage.

16. Transducer apparatus as set forth in claim 15, wherein said element of said stop means includes portions having straight surfaces of substantially greater dimension longitudinally of the feed screw than the spacing between threads thereon and engaging the feed screw on opposite sides thereof.

References (Jited in the file of this patent UNITED STATES PATENTS 766,115 Petit July 26, 1904 1,785,409 Frykman Dec. 16, 1930 1,941,668 Ellman Jan. 2, 1934 2,266,273 Schiif Dec. 16, 1941 2,318,098 Rieber May 4, 1943 2,446,324 Di Ghilini Aug. 3, 1948 2,672,346 Roberts Mar. 16, 1954 2,702,710 Conrad Feb. 22, 1955 2,714,010 Gruber et a1. July 26, 1955 FOREIGN PATENTS 433,614 Great Britain Aug. 19, 1935 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No.- 2 970,84l February 7, 1961 Alfred Lorenz It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below'.

Column 9 line 12, for the claim reference numeral "10" read 9 -a Signed and sealed this let day of August 1961;

EAL Ai t stz ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

